Towards a typology of tone system changes

Most general discussions of tonal change are concerned with the issues of tonogenesis and tonal splits, i. e. the questions of how non-tonal languages become tonal and how these tones later split to produce more tones. In this article I am concerned with two issues: (i) how tone systems acquire more tonal contrasts; (ii) how tone systems lose tonal contrasts. The first issue concerns both laryngeal factors as well as the natural pitch effects that tones have on each other. The second concerns both tonal mergers as well as the restriction of tonal contrasts to certain positions of the word or phrase, which may ultimately lead to tonoexodus, the complete loss of tone.